The Australian Government is planning to introduce legislation that would allow asylum seekers who reach the Australian mainland by boat to be sent offshore for processing.

The new legislation would excise the entire mainland from Australia's migration zone as part of efforts to stop asylum seeker boats.

A move to change the migration zone is just one of 25 recommendations put forward by the Australian Government's expert panel on asylum seekers, and which the Government has committed to introducing.

At the moment, asylum seekers who reach the Australian mainland by boat can't be transferred offshore for processing, unlike those who arrive in excised territories like Christmas Island. The Australian Government wants to change the law so all asylum seekers can be sent abroad to have their refugee claims assessed.

The Immigration Minister Chris Bowen says the move will mean there will be no incentive for asylum seekers to risk their lives trying to reach the mainland.

Very few asylum seekers do make it to mainland Australia by boat with the vast majority intercepted in the surrounding waters.

It is understood the last time asylum seekers reached the mainland was in April this year, when a group of Chinese national arrived on Australia's north coast. Before that was in 2008 when a group of Sri Lankan's landed in Western Australia.

Policy backflip

It is similar to a plan put forward by the former Howard government in 2006, which Labor bitterly opposed at the time.

The Opposition has accused Labor of plumbing new depths of hypocrisy.

"With such a backflip... the Government surely must just come clean and say they were wrong to abolish the proven measures of the Howard government that were working when they came to office in 2007," Opposition immigration spokesman Scott Morrison said.

"Just when you think this Government's hypocrisy on the issue of our borders cannot get any lower, they exceed all expectations."

Immigration Minister Chris Bowen plans to introduce the legislation tomorrow, having discussed the move with caucus colleagues this morning.

In 2006 as an opposition MP, Mr Bowen described the Howard government's plan as a "hypocritical and illogical bill" with no redeeming features.

"If it is passed today, it will be a stain on our national character," Mr Bowen said then.

"The people who will be disadvantaged by this bill are in fear of their lives and we should never turn our back on them."

Mr Bowen said at the time that if the legislation was passed, an incoming Labor government would repeal it.

According to a caucus spokesman, only two MPs raised questions during this morning's discussion and they related to whether the changes were in keeping with Australia's international obligations.

Mr Bowen is adamant they are.

"Our legal advice is very clear, that this is in keeping with our obligations - particularly under the refugee convention," Mr Bowen told ABC News 24.

"I've come to learn over the last two years, that immigration decisions, particularly around asylum, can be controversial.

"But the Government and the caucus are fully supportive of the efforts to save people's lives to get a fairer and orderly process.

"These are difficult decisions for everybody, but we do need to have in place a properly integrated system which says to people there is a safer way of getting to Australia."

'Un-Australian'

According to the expert panel, led by former Defence Force chief Angus Houston, the move to excise the mainland would complement offshore processing arrangements in Nauru and Manus Island.

"Such an amendment will be important to ensure that introduction of processing outside Australia does not encourage asylum seekers to avoid these arrangements by attempting to enter at the Australian mainland," the report states.

As a result of the legislative changes, all asylum seeker arrivals would be processed offshore regardless of how they arrive.

MPs from Labor's Left faction, who have voiced concerns about the move in the past, concede there is not much they can do about the change given they have previously endorsed the Houston report's findings.

But the Greens are vowing to fight the legislation, arguing it undermines the right of refugees to seek asylum in Australia.

"This is a shameful piece of legislation that discriminates against some of the most vulnerable people in our region based on the way in which they arrive in Australia," Greens senator Sarah Hanson-Young said in a statement.

"Rather than trying to help these vulnerable people, this Labor Government is now going to try to enact legislation that is so discriminatory and un-Australian that John Howard faced an internal revolt when he tried it in 2006."